1. Field of the Invention
This invention refers to an examination light and more particularly to a lamp and optics with mounting means supported on an arm that is moveable through two planes, vertically and horizontally, and additionally to the mounting means which is rotatable in two planes about its own axes, and to the separation of the energy emitted by the lamp in to white light and infrared heat and to the redirection of the white light for illumination purposes and to the elimination of the infrared heat from the mounting means.
2. Description of the Prior Art
Moveable mounted examination lights have long been known. They are used in the medical field for illuminating specific areas of the body for specific office or surgical procedures. They are used by designers and draftsmen illuminating and examining their work. And they are used by artisans to increase the visibility of the products upon which they labor. Lights of this nature vary in design from the simple "Goose Neck" (flexible tube) with an incandescent bulb and reflector on its end to the sophisticated counterbalanced surgicallight with high intensity lamps and complex optics. between these extremes are lamps supported on articulated structures incorporating springs and friction joints such as that of Scattolin et. al. U.S. Pat. No. 4,213,172, which is a typical drafting table type device, or that of Mathers, U.S. Pat. No. 4,494,177 of similar design. In contrast, Sowden et. al. U.S. Pat. No. 4,165,530 presents a more intricate design, whereby two separate friction elements are combined in one hub to independently stabilize two separate sections of a lamp supporting arm.
There are innumerable designs incorproating springs as a means for counterbalancing supporting arms, however most of them do not provide an exact relationship to oppose the gravitational forces on the arm at all points through its freedom of travel, and therefore must rely on frictional forces at the pivots to restrict motion at the positions of imbalance. Such is the case with the art of Saluja U.S. Pat. No. 4,107,769. Saluja, similar to many others, utilizes a compression spring within the lumen of a tubular arm to provide a hidden counterbalance means. All spring arrangements of this type can at best provide exact balance only at two nodes throughout the half arc freedom of motion of the arm.
the only method whereby an exact spring counterbalance could be achieved for all positions of such an arm is by the use of a cam and spring loaded cam follower design to exactly match the springforce and the gravitational force on the arm. Even so, a cam design, because of the requirement for small size, has to be made so highly loaded by the required spring force that the frictional forces produced at the pivots and in the bearings obviates the effect of the near perfect balance. Hence the value of such a design is questionable.
In addition to their primary purpose support arms and structures must provide motion in a horizontal plane. To this purpose the base end of the arm or structure usually is attached to a vertical shaft retained in a base structure. Bearings either in the base structure or in the arm attachingmeans permits the horizontal rotation. In mounted medical lights the base structure is attached to a pole which projects from the mounting arrangement.
Independent rotation of the support means for the lamp and optics mounted at the end of the arm are accomplished usually by one of three basic methods, the most common and simple of which is the use of a captured ball clamped between cup sockets held together by a screw means which applies friction to the ball, thereby preventing motion between the two. One element, usually the ball, is affixed to the support means and the other element, the sockets, is a component of the arm. Movement of the support means is accomplished by manually overcoming the friction of the ball and sockets.
Another basic method is by the use of two frictional pivots in orthagonal planes. One provides rotation about the axis of the support means, and the other permits the support means to be rotated through an arc in a vertical plane about an axis positioned very close to the support means.
A third basic method, and one used mostly in the medical field, is that of gimbal mounting the support means. This method is utilized where it is desireable to eliminate unwanted frictional resistance to the movement of the lamp and optics support means. It consists of a yoke, or gimbal, which incorporates axial aligned pivots, one on either side of the support means, along a transverse axis of the support means which is located at its transverse center of gravity. Thus, the support means is in balance about its transverse axis and thus can be easily rotated and will remain at any angle at which it is placed. Similarly, the yoke is pivoted along the longitudinal axis of the support means at its longitudinal center of gravity, thus providing similar ease of movement and balance along the longitudinal axis.
The lamp which is the luminous source for the examination light can be of several types. Initially, incandescent lamps of the home variety were used exclusively, and still are, for draftsmen and artisan type lights and for some medical lights. These have been augmented by fluorescent lamps, which are advocated for certain applications. High pressure gas arc lamps are also used as a luminous source for some special applications, however, the electrical complexities required to operate them and the need for sophisticated optical projection systems to use them, severely limits their application. The use of halogen type lamps has become the standard source for use in medical lights. Because of their higher filament temperature they provide a whiter, brighter, and smaller source for illumination than all others with the exception of the high pressure gas arc. However, the halogen lamp does not require any special electrical circuitry and as a source is sufficiently larger than the arc to accomodate the use of ordinary optical elements for projection.
Light from the illumination source is directed to the examination area by means which range from simple non-optical white painted reflectors, to complex and intricate optical projection systems. Most commonly, a single optical reflector is used to collect light from a large solid angle about the source, and reimage the source in the examination area.
In many instances, such as with medical lights, it is desireable to render the light as white, or as close to that of sunlight as possible, in order to provide the observation of color as true as possible. Two filtering methods are used to render the light whiter. One method utilizes an absorption filter between the source and the target or examination area. The absorption filter absorbs or reflects back toward the source the infrared heat from the lamp and allows only the whiter light to pass through to the target. Another method is by the use of a pass filter. a pass filter is usually incorproated in a reflecting element in a manner such that it reflects only the white light to the target area. The filter permits the infrared to pass through the reflecting element and out of the optical system.